Or you can use the special tags [ url ][ /url ] . Insert them using the Blue Globe icon, second from left, bottom row above. The tool tip when you hover over it says "Insert Hyperlink" That will insert "[ url ][ /url ]" into the code.

e.g.[ url ]www.YOURURL.com[ /url ]

You can also have true hyperlinks using the [ url ] code. Just use the following format:

[ url=http://www.YOURURL.com ]the name of the website[ /url ]

Note: extra spaces have been added to the tags so that they display, rather than work.